Chicago - The number of US poultry flocks infected with a deadly strain of bird flu rose on Tuesday as Iowa identified its first case and Minnesota confirmed eight more cases, according to the US Department of Agriculture.
Iowa became the 12th state this year to find poultry infected with the H5N2 flu, which can kill nearly an entire flock within 48 hours.
Twenty-two commercial turkey flocks in Minnesota, the leading US turkey-producing state, have been infected with the H5N2 flu in about six weeks. That accounts for more than half of the 43 flocks nationwide that have been infected since the beginning of the year, according to Agriculture Department data.
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Facilities with newly confirmed infections will be quarantined and birds there will be culled, according to the department.
Prior to Minnesota's eight new cases, poultry producers in the state had lost about 900 000 turkeys worth $15.7m due to deaths from bird flu and culling to prevent the spread of the disease, the Minnesota Turkey Growers Association said. Farmers in Minnesota raise about 46 million turkeys a year, according to the association.
Bird flu infections have prompted major overseas buyers, including China and Mexico, to restrict imports of US poultry and eggs in the $5.7bn export market.
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Birds grown for major poultry producers including privately held Butterball LLC, Cargill and a subsidiary of Hormel Foods have been killed by the virus this year.
Migratory ducks are believed to be spreading the virus as they travel to northern states after spending the winter farther south, veterinarians have said.
No human cases of bird flu have been reported.